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Painting in OpenGL
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I use OpenGL to create interactive digital art. These images are from an artwork that's in a gallery show in New York city.
The images are created by "painting" with a 3D model. The model is drawn with very low alpha into a screen-sized textur... |
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Posted November 30, 2005 11:07:16 PM
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Question about blending and depth test
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If I draw a translucent shape over a scene, with depth test enabled, shouldn't the hidden faces behind the translucent shape be removed?
In this case I'm drawing a head in front of a cube (image below). The cube shows through the head, and so... |
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Posted September 18, 2005 11:29:30 AM
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can framebuffer ALPHA_BITS be set
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I'm getting odd results with alpha blending on different graphics cards. I'm hoping somebody out there can check my logic below and tell me if I'm understanding this correctly.
I'm rendering many overlapping textured layers with very faint a... |
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Posted May 31, 2005 11:24:21 PM
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line_strip changes when texture's enabled
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I'm drawing line strips, with blending enabled. When I enable GL_TEXTURE_2D I notice that the blending changes slightly, it gets a little fainter. This becomes noticeable if several lines are overlapped.
Do textures affect the rendering of lines... |
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Posted February 14, 2005 12:41:07 AM
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blending question: GL_ONE_MINUS_CONSTANT_COLOR
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Does anybody know what the GL_ONE_MINUS_CONSTANT_COLOR param does, as in:
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_CONSTANT_COLOR);
I haven't found any explanation of what the "constant_color" is referring to or what the purpose i... |
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Posted December 11, 2004 12:25:22 AM
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glCopyTexSubImage distorts colors
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I'm using glCopyTexSubImage2D to grab the framebuffer into a texture. Later I draw that texture on a screen-sized quad. The problem is that the colors of the restored screen image looks slightly different than the original. If I capture the l... |
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Posted November 2, 2004 6:05:40 PM
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| Some recent replies made on our forums |
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Painting in OpenGL
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You 'paint' by moving the 3D model (using a mouse), which leaves a trail behind as it moves. The code places the model in a space and does the rendering, but the images that you see above are a result of the motions and gestures of a person intera... |
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Posted December 5, 2005 5:45:48 PM
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Painting in OpenGL
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Quote:Wasn't there something about you on OpenGL.org?
That's true, I sent them some info a few weeks back, which they posted.
I'm a big fan of OpenGL :-)
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Posted December 2, 2005 4:23:00 PM
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Painting in OpenGL
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Thanks for the replies, folks.
Quote:The red traced image is that of the World Trade Center.
Actually the model is the Empire state building, but it's textured with an image from the WTC. The tower's collapse radically altered my trust in... |
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Posted December 1, 2005 10:52:11 PM
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Question about blending and depth test
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Thanks for the clarification and suggestions.
Mikeman, the two-pass rendering gave me exaclty the effect I was looking for. Thanks.
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Posted September 18, 2005 1:10:18 PM
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can framebuffer ALPHA_BITS be set
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Thanks for the reply zedzeek.
1) My display is set to 32 bit color.
2) I'm not sure how to set dithering on a mac, I'll look into it.
3) My texture internal format is RGBA8 (other formats like RGBA,
RGBA16 give the same results).
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Posted June 1, 2005 7:26:47 AM
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blending question: GL_ONE_MINUS_CONSTANT_COLOR
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Thanks for the help. |
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Posted December 11, 2004 8:02:00 PM
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glCopyTexSubImage distorts colors
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Thanks for the help. Using GL_RGBA8 in the glTexImage2D() call did the trick. Works perfectly now.
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Posted November 3, 2004 1:27:41 PM
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View All Replies Made By This User
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